The present invention relates to a process for winding a newly joined thread onto a tube newly inserted on a spooling device on an open-end spinning mechanism, and to an apparatus for carrying out this process.
It is known, after the machine has stopped, to join the thread anew by means of a thread resupplied from a starter bobbin and subsequently to wind the thread portion containing the leader onto this starter bobbin, whereupon, without an interruption in the spinning operation, the starter bobbin is exchanged for an empty tube to which the thread is then transferred. In this case, the start of winding onto the newly inserted empty tube does not involve any new thread-joining, so that the start of the bobbin has no leader although a starter bobbin is necessary for thread-joining.
It is also known, in connection with a bobbin change, to interrupt the spinning operation at the particular spinning unit to clean the spinning element and to join the thread anew (Sussen-WST-Technische Mitteilungen: "Automation of the rotor-spinning machine with CleanCat/CLC and SpinCat/SPC--Aspects and Perspective--", page 23, paragraph 3.12: "Elimination of thread breaks which arise during the bobbin change--"interrupted bobbin change"--"). In this case, however, the leader obtained passes onto the bobbin. This leader represents, as a rule, a thick or thin place and therefore an irregularity in the yarn and is consequently undesirable.
To prevent leaders from passing onto the bobbin, it is also known to replace the leader by a knot (German Offenlegungschrift No. 2,242,151, claim 3). Although knots have the advantage that they do not reduce the yarn strength, nevertheless, they also form an irregularity in the yarn. It is, therefore, desirable for further processing that the yarn should contain as few knots as possible. Besides, during further processing of the yarn, the thread end of a running-off bobbin has to be connected to the thread start of a new bobbin so that bobbin connecting knots of this type are unavoidable. However, in addition to these connecting knots there are also, directly adjacent to them, the knots which replace the attachment points. In order to do away with knots of this type which replace the attachment points, the bobbin coming from the open-end spinning unit has to be wound round in an additional operation, this knot, which replaces the leader, then being severed.